1. Field of the Invention
The present invention relates to a light emitting display.
2. Description of the Related Art
A light emitting device used in a light emitting display is an active light emitting device in which a light emitting layer is formed between two electrodes. The device is classified into an inorganic light emitting device and an organic light emitting device depending on the light emitting material. The light emitting device is also classified into a passive matrix type device and an active matrix type device depending on the driving method of light emitting layer.
The lifetime of a light emitting display is determined mainly by driving time of the display and degradation of the light emitting device.
The degradation of the light emitting device is caused by heat generated internally and, oxidation of the device by oxygen and moisture permeated into the device, resulting in a reduction of the light emitting area therein.
Such problems are common to active matrix type and passive matrix type light emitting devices. Specially the active matrix type device experiences more heat-related problems than the passive matrix type device. In a device with a larger light emitting area, the center part generates heat of a higher temperature than the outer part.
FIG. 1 is a sectional view of a conventional light emitting device.
Referring to FIG. 1, a light emitting display 100 comprises a pixel circuit part (P) having a first electrode 120, a light emitting part 130, and a second electrode 140 formed on a substrate 110. The first electrode 120 is patterned and insulated by an insulating layer. The organic light emitting part 130 is formed on the first electrode 120, while the second electrode 140 is formed on the light emitting part 130. The substrate 110 is covered with a shield cap 160 and is sealed with a sealant 170 to protect the pixel circuit part (P) from oxygen and moisture permeated into the device.
An getter 150 is inserted into the display 110 for absorption from moisture and/or oxygen. A heat sink 180 is adhered to an outer surface of a shield cap 160 by adhesive 185 for preventing degradation of the display 100 by heat
However, since a light emitting display 100 as above is relying solely on the heat sink 180, its capacity to discharge heat generated in the pixel circuit part (P) is very limited.